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7/29/2019 Chuong7-Vat Lieu Com
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VT LIU COMPOSITE
TRNG I HC BCH KHOA THNH PH H CH MINH
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COMPOSITE
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COMPOSITE
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COMPOSITE
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COMPOSITE
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TNG QUAN
Ti sao chng ta li quan tm ti vt liu composite ???
Tnh cht cc vt liu truyn thng
Kim loi: bn, do, nng
Polyme: bn khng cao, tuy nhin rt do v nh
Ceramic: cng, dn, rt bn vi nhit ,
Chng ta c th to ra vt liu c nhng tnh nng u vit
ca mi loi vt liu truyn thng khng ????
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Vt liu composite l vt liu t hp t hai hay nhiu loi vt liu c bn cht khcnhau. Vt liu to thnh c nhng c tnh tri hn c tnh ca hai vt liu thnh
phn khi xt ring l
I. KHI NIM
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I. KHI NIM
Nn L pha lin tc ng vai tr:
Lin kt cc phn t ct thnhkhi composite ng nht.
Che ph v bo v ct trnh cch hng c hc v ha hc cami trng.
Truyn ti v phn b ti trngsang vt liu ct lm gim ng
sut tp trung.To kh nng d dng tin
hnh cc phng php gia cng
composite thnh cc chi tit theo
thit k
Ct l pha gin on ng vai tr
To nn bn cao, modul n hi
cao cho composite
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I. KHI NIM
Ct l pha gin on ng vai tr to nn bn cao, modul n hi cao
cho composite
Cc yu t nh gi
Tnh gia cng c hc
Tnh khng ha cht, mi trng , nhit
Kh nng phn tn vo trong nn
C thun li cho qu trnh gia cng hay khng
Gi thnh
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- Gi thnh r hn thp khng g.
- T s tnh nng c l/gi c v t s tnh nng c l/ khi lng cao hn st
thp nhiu.
- Nh.
- Phng php gia cng ch to n gin v a dng.
- D to hnh thay i, sa cha.
- Chi ph u t thp.
II. C IM CA VT LIU COMPOSITE
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II. C IM CA VT LIU COMPOSITE
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Nguyn tc gia cng trong vt liu composite
Khi lc tc dng vo n, chng s bchuyn hng, to thnh nhng lung
lc mi c cng yu hn, sau nhiu
ln chuyn hng v truyn mt phn
lc cho n, cho nn th lc b trit tiu
hon ton
Khi lc tc dng vo n, mt phn lc
s b ht n hp thu, phn cn li s
c truyn sang ht n khc, kt qu
l lc tc dng s gim dn cng v
b trit tiu sau khi i qua nhiu ht n
F1
F2
F3
F1>F2>F3
n cng
n mm
F
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Mi vt liu u c nhng tnh cht ring v rt c trng ty theo yu cu v
tnh cht ca vt liu composite m chng ta la chn vt liu cho ph hp. Mt
im cn quan tm na l s khc bit v khi lng ring ca hai pha s
nh hng rt ln n sn phm.
V d: vt liu composite t gang v silicabit (SiC). Do dsilicabit
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Lin kt ha hc
V d: composite gia si thy tinh vi nha c cha silan
S kt dnh gia ct nn
y l yu t quyt nh n c tnh ca vt liu composite. Cc dng kt dnh gia
ct v nn l:
Cc yu t nh hng n tnh chtcomposit
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Lin kt tnh in
Lin kt c hc: xut hin khi c s tip xc trit gia hai pha, ph thuc vo
din tch tip xc gia hai pha.
Cc yu t nh hng n tnh chtcomposit
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Khe khng kh
n
Nn Bt kh
Lin kt cng cc
V d: to b tng gm ct, , xi mng v thp c du trn b mt, do xi mng
phn cc, trong khi du khng phn cc lm cho s tip xc gia xi mng vthp khng tt, lm cho tnh nng ca b tng ct thp khng cao.
Thng thng cc yu t lm nh hng n tnh kt dnh hay tnh cht ca vt liu
l do s hp ph v thm t khng tt, linh ng ca vt liu nn ( nha):
Cc yu t nh hng n tnh cht composit
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Uniaxial
constraint
Cc yu t nh hng n tnh chtcomposit
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Thng thng c tnh ca vt liu composite s tng khi ta tng hm lng n
(ct), tuy nhin ch tng ti mt mc no , nu tip tc tng hm lng n
ln, c tnh s gim dn.
T l nn/ct
c trng hnh hc ca vt liu tng cng
c xc nh bi : hnh dng, kch thc, tp trung v phn b:
Cc yu t nh hng n tnh chtcomposit
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Phn b khng u Phn b u
Cc yu t nh hng n tnh cht composit
S phn b:
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Cc yu t nh hng n tnh cht composit
Hnh dng
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Cc yu t nh hng n tnh cht composit
Kch thc:
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Trong trng hp composite vi cht n dng si, phng ca si quyt nh
tnh d hng ca vt liu.
Cc yu t nh hng n tnh cht composit
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C nhiu phng php gia cng nhng phng php no cng cn m bo phn
tn u cht n trong pha nn. Ngoi ra, lm cch no gim thiu cc khuyt tt
trong qu trnh gia cng nh bt kh, qu nhit cng l mt trong cc yu t quyt
nh n tnh cht ca vt liu composite
Phng php gia cng composit
Cc yu t nh hng n tnh chtcomposit
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Phn loi
Theo bn cht v thnh phn
Composite nn hu c(PMC)cng vi vt liu ct dng:
Si hu c: Polyamit, kevlar
Si khong: thy tinh, cacbon
Si kim loi: Bo, nhm
Composite nn kim loi(MMC)vi n dng ht:
Si kim loi: Bo
Si khong: Cacbon, silic
Composite nn ceramic (CMC)vi vt liu ct dng:
Si kim loi: Bo
Ht kim loi.
Ht gm.
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Theo hnh dng n
Phn loi
Composite gia cng bng ht:
Ht c nhiu dng hnh hc khc nhau nhng nhn chung kch thc ca
chng tng i ng u theo mi hng.
gia cng hiu qu, ht phi nh v phn tn ng u trong nn.
C th phn thnh composite ht th v ht mn ( < 0.1 micromet).
Gm c:
Composite nn kim loi
composite nn ceramit.
Composite nn polyme
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composit ht th l btng:ximng l nn, ct v si l ct.
composit ht mn: cao su n
than en kch thc ht 20 50 nm
Phn loi
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Ru l nhng n tinh th rt mng vi t l gia chiu di v ng knh l rt ln. N
khng tn ti khuyt tt nn bn rt cao, v vy rt t tin. c bit ru tinh th rt kh
lin kt vi vt liu nn. Nhng vt liu ru tinh th bao gm graphite, silicon carbide,
silicon nitride, aluminum oxide.
Vt liu lm si dng a tinh th hoc v nh hnh c ng knh nh, thng thng l
polymer hoc ceramic ( polymer aramids, glass, carbon, boron, aluminum oxide, siliconcarbide).
Dng dy c ng knh ln hn, nhng vt liu in hnh nh: molybdenum v tungsten.
Dy c dng nh nhng si thp gia cng trong lp xe t.
Theo hnh dng n
Phn loi
composit gia cng bng si
Mt s dng si:
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Theo dng cu trc
Phn loi
Cu trc lp:
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Bao gm 2 lp mng cng bn
ngoi bao bc mt lp li dy
bn trong.
To nn mt cu trc nh nhng
c cng v bn tng i
cao.
Phn loi
Theo dng cu trc
Composit dng sandwich
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M hnh trn m t composite sandwich (A) v cc thnh phn ca n
gm: cc tm mt (B) v li c cu trc t ong (C)
Cu trc t ong thng thng lm t hp kim nhm hoc polymer aramid.
Composit cu trc sandwich c nhiu ng dng: tm lp mi, sn, tngtrong xy dng, hoc cnh, thn my bay, mt phn ui my bay.
Composit dng t ong
Theo dng cu trc
Phn loi
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Cng ngh ch to vt liu composite nn polymer
Gia cng bng tay ( hand-lay-up):dng c hay con ln qut nha ln khun ph chng dnh, t vi ln, qut nha, dng con ln ui bt kh v ln cht, tip tc
nh th cho n khi t yu cu.
Gia cng p sut thng
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Chi ph u t thp
Quy trnh n gin v linh hot. C th s dng nhiu loi si v nh hng
si khc nhau
Thch hp sn xut cc sn phm c kch thc ln
Cht lng sn phm ph thuc nhiu vo tay ngh nhn cng.
ng u ca sn phm khng cao
Khun h cho nn gp nhiu vn v dung mi c hi, d bay hi.
Khng thch hp sn xut cc sn phm c kch thc nh, tinh so cao.
U IM
NHC IM
Cng ngh ch to vt liu composite nn polymer
Gia cng bng tay ( hand-lay-up)
C
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Phng php phun nha si ( spray-up):si
th c ct ngn phun vo cng lc vi nha
tun t cho n khi t b dy yu cu, dng conln ui bt kh.
Gia cng p sut thng
Cng ngh ch to vt liu composite nn polymer
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C h h t t li it l
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Thch hp sn xut cc sn phm c kch thc va v ln, c mtkhun un ln.
Chi ph u t thp.
Khng thch hp sn xut cc sn phm c tinh so cao.
Kh kim sot c t l nha si, b dy sn phm. Nhng thng s
ny i hi tay ngh ca ngi cng nhn.Khun h cho nn vn v c hi ca dung mi cn phi c
quan tm.
Ch to c mt mt lng
U IM
NHC IM
Phng php phun nha si ( spray-up)
Cng ngh ch to vt liu composite nn polymer
C h h t t li it l
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Phng php cun si ( filament Winding) :
cun si c ko qua mng thm nha trc,
sau cun ph ln mt khun, dng snxut ng dn, thng cha nh
Gia cng p sut thng
Cng ngh ch to vt liu composite nn polymer
C h h t t li it l
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Thch hp sn xut cc bnh, ng chu p sut.
Thch hp sn xut cc sn phm c kch thc khc nhau
Chi ph u t thp: nguyn liu u vo r, h thng thit b khng qut so vi mt s phng php khc.
C th tin hnh mt cch t ng
Hn ch trong sn xut cc sn phm c cu trc kn, vi nhng cu
trc h ( bn tm) th phng php ny khng thc s thch hp
Kh kim sot c ng u v t l nha si trong sut b dy
sn phm.
U IM
NHC IM
Phng php qun si ( filament winding)
Cng ngh ch to vt liu composite nn polymer
C h h t t li it l
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Gia cng di p sut
Cng ngh ch to vt liu composite nn polymer
c p nng ( hot press moulding):nha si
hay n c trn u, cho vo khun c
di p sut v nhit cao, sn phm c
nh hnh theo 3 chiu
Cng ngh ch to vt liu composite nn polymer
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c p ngui ( Cold press moulding):ging c p nng nhng tin hnh nhit
thng.
Gia cng di p sut
Cng ngh ch to vt liu composite nn polymer
Cng ngh ch to vt liu composite nn polymer
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C th sn xut c cc sn phm c t l si cao.
C th sn xut cc sn phm c kch thc t nh cho ti ln.
Nng sut cao.
Khng i hi nhiu nhn cng
bng lng b mt, chnh xc cao v thch hp cho vic sn xut
cc chi tit c tinh so.
Hn ch trong vic sn xut cc sn phm c hnh dng n ginnh a phng.
Kh sn xut cc sn phm i hi b dy ln.
D gy h hng khun, to nhiu bavia.
Chi ph u t cao.
U IM
NHC IM
Cng ngh ch to vt liu composite nn polymer
Gia cng di p sut
Cng ngh ch to vt liu composite nn polymer
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n ko ( pultrution):cht n trn vi nha np lin tc v ko qua li c gia
nhit, nha ng rn mt phn hay hon ton khi qua li to hnh.
Cng ngh ch to vt liu composite nn polymer
Cng ngh ch to vt liu composite nn polymer
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Qu trnh din ra lin tc, nng sut sn xut cao, chnh xc cao.
Qu trnh din ra gn nh t ng, khng cn nhiu nhn cng lnh ngh.
Thch hp sn xut cc sn phm c mt ct ngang khng i dc theochiu di.
Chi ph u t cao.
Khng thch hp cho cc sn phm c hnh dng phc tp, b dy mng.
Nhng sn phm cn kh nng chu lc phc tp khng c sn xut
theo phng php ny do cc tnh cht ca chng phn ln b hn ch theo
hng dc trc.
U IM
NHC IM
Cng ngh ch to vt liu composite nn polymer
n ko ( pultrution)
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Cng ngh ch to vt liu composite nn polymer
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c tim ( injection):n cho vo khun, sau nha lng tim vo khun, gia
nhit ng rn. Cng c th trn nha v n trc ri tim vo khun, ng
thi phn ng ng rn xy ra trong khun.
Cng ngh ch to vt liu composite nn polymer
Cng ngh ch to vt liu composite nn polymer
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Kh nng t ng ha cao.
Nng sut cao.
C kh nng sn xut cc sn phm c kch thc va v nh.C th sn xut cc chi tit tinh so c chnh xc cao.
Chi phi u t cao.
Yu cu p sut ln, d gy h hng khun.
Ch c th s dng cho cc loi si ct ngn.
U IM
NHC IM
Cng ngh ch to vt liu composite nn polymer
c tim ( injection)
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